A method is described for comparing microscopically the cross-sectional areas of the same cotton fiber in wet and dry conditions, for evaluation of swelling. Results indicate the change in cross-sectional area of raw cotton fibers to be between 21 % and 34% of the dry area regardless of variety of cotton or degree of maturity of the fiber. Immature samples show slightly less mean swelling than mature samples, but this is believed to be due to the presence of fibers with no secondary thickening at all which tend to shrink in cross-sectional area rather than swell. In the immature fibers deformation (defined as change in circularity) is slightly more than that of mature fibers. This, coupled with the fact that in a given weight of immature fibers there are approximately twice as many fibers as in a like weight of mature fibers, helps to explain the greater closing capacity of yarns made from immature cotton. Flax and a sample of viscose rayon show twice the swelling of cotton, Fortisan two-thirds as much, and nylon no crosssectional swelling at all.

SUMMARY Five fractions of parenchymatous cells of the cotyledon of the peanut were isolated by homogenization and differential centrifugation from nonaqueous media. These are two protein‐rich fractions (one of which appears to be aleurone grains), starch grains, a fines material, and cell wall fragments. In addition, a fraction composed largely of vascular tissue of the cotyledon was isolated. The nitrogen of the cell is concentrated in the two protein‐rich fractions, phytin in the aleurone grains, sucrose mostly in the fines fraction and to a lesser extent in the starch granules, and ribonucleic acid in the fines fraction. The proteins in both protein‐rich fractions appear to be the same as judged by chromatography and zone electrophoresis.

The primary wall of fully matured cotton fibers has been isolated and its morphology and composition studied by electron microscopic examination and by chemical analyses. The pri mary wall appears to contain about 50% cellulose; protein, wax, and pectic substances occur in lesser amounts; cutin or suberin and mineral matter are also present. The concentration of noncellulosic substances in the primary wall is much greater than in the whole fiber. Electron microscopic examination of the primary wall indicates that it consists of a network of cellulose fibrils, having diameters of 100-400 Å, surrounded by the noncellulosic constituents. The oriented fibrillar systems observed with the polarizing microscope have not been seen in the electron micrographs of the specimens studied. There is an apparent increase in the diameter of the fibrils of the primary wall and in the denseness of the network as the fiber matures. The existence of layers in the cellulose network has been observed.

The topography and structure of the primary wall of the cotton lint fiber are described and illustrated by electron micrographs. The changes in this thin membrane brought about by alkali boil (kiering), hypochlorite and peroxide bleaching, mercerization, acid hydrolysis, and dry heat are shown by means of microscopical examination of isolated pieces of the primary wall after exposure to these environments. The noncellulosic constituents of the wall, which account for a large part of its chemical composition, are progressively removed during alkaline kiering. Excessive conditions of kiering appear to damage the cellulose framework of the wall. Peroxide bleaching is apparently effective in removing the encrusting noncellulosic material, but hypo chlorite alone does not have this effect. Mercerization of the isolated wall induces shrinkage in both longitudinal and transverse directions; the shrinkage increases when the noncellulosic materials are removed from the membrane prior to mercerization. The morphology and struc ture of the wall account for the observed behavior on mercerization, and electron micrographs of the mercerized wall show a shrunken network of cellulose fibrils. The primary wall shows resistance to disintegration by acid hydrolysis, and its fibrillar pattern is preserved intact, after long periods of contact with hot mineral acid. Long periods of heating in air "set" the primary wall in a configuration similar to that which it had on the corrugated surface of the cotton fiber. The contribution of the primary wall to certain gross properties of the fiber and its behavior during finishing treatments is discussed.

A method is described for isolating the lumen contents of the cotton fiber by digestion of the cellulose in chilled 72% sulfuric acid. Microscopical observations on the isolated "lumens" as well as the lumen in the whole fiber are reported. The isolated lumens appeared tubular in shape, and electron micrographs of thin sheets of the membrane material showed an unoriented, granular structure. The lumen residue isolated by sulfuric acid was found to be completely hydrolyzed by 1% sodium hydroxide, but only partly hydrolyzed in dilute mineral acid. Amino acid determination by paper chromatography disclosed no free amino acids in the lumen material; but in an acid- hydrolyzed sample, glutamic and aspartic acids, valine, alanine, and probably serine and arginine were found, in addition to several unidentified amino acids.